This invention generally deals with ventilation systems for buildings and pertains more particularly to apparatus for controlling the operation of ventilation doors to provide emergency building ventilation in the event of an electrical power failure.
The use of rather large, enclosed building structures especially adapted for maintaining animals in close confinement is a common practice in commercial livestock operations. In pig farrowing operations for example, it is normally desired to closely crowd the pigs within the enclosed structure so that a minimum of free space is available for the animals to roam about; in this manner, not only can a maximum number of animals be protectively enclosed from the outside elements within a limited area of floor space, but the animals are prevented from wasting fat energy through excess exercise and thus fatten for market more quickly than would otherwise occur if the floor space were less densely crowded. As a result of these close crowding conditions however, the air within the structure becomes quickly stale, and perhaps more importantly, the temperature within the structure, particularly at the floor level near the animals, quickly rises due to the substantial body heat given off by the animals. Young animals particularly pigs, are especially vulnerable to the adverse affects quickly brought on by stale air and excess temperature consequently, substantial ventilation systems are normally installed in these animal confinement structures to draw in fresh outside air from the atmosphere and expel the stale air from the structure to provide continuous, positive ventilation of the structure at all times.
Known ventilation systems presently in use typically employ electrically powered fan means for moving the air. In rural installations, electrical power outages are rather common, especially during the hot summer months when storms are often responsible for interrupting commercial power service. In some cases, emergency electrical power generators may be on hand to maintain power service to the ventilation fans when the commercial service is cut off, however the capital investment needed to provide backup power generation is substantial compared to the relatively short duration of time which this type of power is actually used. The need to provide constant ventilation in livestock confinement structures is absolutely critical, since, in the absence of adequate ventilation, the closely crowded animals may die from suffocation within a matter of minutes and an entire herd of livestock may be lost due to a temporary power failure. Apart from the use of a local emergency electrical power supply generator mentioned above, another possible means of protecting against suffocation of livestock is to provide a plurality of ventilation doors in the structure which are normally closed but which may be opened to create a ventilating draft which flows through the structure in the event of an electrical power lost. One way of implementing this last mentioned approach is to provide a signalling means remote from the confinement structure for alerting the farmer or other operating personnel that power to the ventilation fans has been lost, at which time the emergency ventilation doors may be manually opened. However, this last discussed approach has obvious disadvantages; for example, personnel must be available at all times to detect the loss of power service--this requirement is impractical where the livestock operation is run by a single individual. Moreover, in the case of especially large livestock operations involving several large confinement structures, considerable time might be required to manually open the multiplicity of ventilation doors which must be opened to provide adequate ventilation. It is not uncommon, especially in rural areas, for electrical service to be interrupted a number of times within a single day, consequently, the use of manually operated emergency ventilation doors as described above is also impractical for the reason that considerable time and effort must be devoted to effecting the opening and closing of the ventilation doors.
From the foregoing, it is apparent that there is a need in the art for an emergency ventilation system including means for simultaneously and automatically both opening or closing a plurality of ventilation doors in response to the presence or absence of commercial electrical power to the conventional ventilation system of the confinement structure.
According to the present invention, a novel emergency ventilation system including unique apparatus for operating a ventilation door includes means for sensing the presence or absence of commercial electrical power service and hydraulically operated power means responsive to the electrical power sensing means for selectively opening or closing an emergency ventilation door. A hydraulically operated bi-state cylinder assembly connected to the door functions to maintain the latter in a closed position under normal circumstances when commercial electrical power is being received, but releases the door to the influence of a spring biasing means which opens the door when the commercial electrical power is interrupted.
An important object of the present invention is to provide an emergency ventilation system for an enclosed livestock confinement structure which is automatically responsive in operation to the presence or absence of commercial electrical power to the structure. As a corollary to the foregoing object, it is a further object to provide means for sensing the absence of commercial electrical power to the structure and providing emergency ventilation of the structure in response to the absence of commercial electrical power.
Another object of the invention is to provide a novel control system for automatically opening and closing a ventilation door in response to the presence or absence of commercial electrical power to the confinement structure.
A further object of the invention is to provide a ventilation system of the type described in which a plurality of door control systems of the type mentioned are employed and are simultaneously operable to open and close the associated doors without the need for direct interconnection of the control systems to achieve the simultaneous operation thereof.
A still further object of the invention is to provide a control system of the mentioned type which is readily adpatable for use with the various types and sizes of ventilation doors.
Another object of the invention is to provide a ventilation system of the type mentioned above which functions to reverse the flow of ventilating air within the structure in response to the loss of electrical commercial power by creating an upwardly directed air draft which draws cool outside air into the structure in the lower regions of the latter and exhausts the warmer air within the structure through upper regions of the latter.
These and further objects of the invention will be made clear or become apparent in the course of the following description of a preferred embodiment of the invention.